In a prior sagittal saw marketed by the Assignee of the present invention, a powered surgical handpiece carries a sagittal saw chuck capable of removably chucking various blades on a one-at-a-time basis. Each of the prior blades has a widened, rounded base perforated by a coaxially located, circumferentially spaced, pattern of identical through holes and a central, rear opening slit. The prior chuck has a bottom member having a pattern of upstanding pins located to enter the through holes in the blade base. A chuck top member has a center post depending through a central opening of the bottom member and spring biased down to pull the top member down onto the top member's upstanding pins.
To load a blade into the chuck requires gripping of three members as follows.
1. The handpiece is fixedly supported.
2. The resiliently downwardly urged top member is pulled upward from the bottom member pins to open the chuck.
3. The blade base is inserted into the now open chuck with its rear opening slit receiving the top member post.
Chucking of a blade requires that the blade be moved in several directions with respect to the handpiece. More particularly, the blade must be inserted horizontally into the open chuck, then the blade must be pivoted horizontally until its holes align with the upstanding bottom member pins, and then the blade base is dropped onto the chuck bottom member.
Then the spring biased chuck top member can be dropped onto the bottom member pins which then enter into a corresponding pattern of recesses in the bottom of the top member which in turn is pulled down to press down on the base of the blade. In this manner, the blade is locked fixedly with respect to the chuck. Removal of a blade from the chuck involves a reversal of the aforementioned steps.
Although the above-described prior chuck and tool have worked well for a substantial period of time, and have been found satisfactory by surgeons, nevertheless, the present Applicant has noted certain drawbacks of the above-discussed prior system, which drawbacks the present invention is intended to cure.
Accordingly, the objects and purposes of the present invention include provision of a surgical tool chuck and blade structure in which full insertion of blade into chuck can be done easily with only two (rather than three) hands; in which a blade is chucked merely by pushing it longitudinally into the chuck while pushing a locking element on the chuck; in which the blade is either obviously insufficiently inserted or is positively locked against escape from the chuck; in which significant insertion of the blade into the chuck requires manual pushing of a locking element; in which such insufficient insertion is made obvious by a number of observables including short insertion distance before insertion is positively blocked, virtually no blade retention force, free pivoting of the blade from side to side and up and down (roll and pitch) with respect to the chuck, and dropping of the blade out of the chuck upon almost any movement of the chuck or handpiece; in which positive locking of the blade in the chuck is present for almost the entire longitudinal insertion of the blade base into the chuck; in which such positive locking prevents the blade from accidentally being removed from the chuck even when the blade is not fully inserted into the chuck; in which the possibility of accidental release of the locking element by careless handling of the chuck or handpiece is minimized; in which a blade can simply be dropped out of its fully inserted and positively locked position in the chuck by one handed gripping of the chuck in a way to push the locking element; in which the blade tends to be seated more firmly in the chuck during cutting; in which locking of the blade in the chuck and prevention of rocking of the blade in the chuck are carried out by different portions of the chuck acting on the blade; in which the chuck can be made more compact than the prior chuck above described, in which the chuck and blade are of simple relatively inexpensive construction, in which blades of a range of differing thicknesses can be inserted in the chuck without any manipulation of the chuck to compensate for differences in thickness and wherein the chuck automatically compensates for differences in thicknesses of blades; in which the number of parts is substantially reduced; in which the blade receiving portion of the chuck is constructible in two facing pieces which can be easily machined and thereafter permanently fixed together as by electron beam welding, and in which the insertion and removal of a blade with respect to the chuck can be carried out by persons without special training and under the adverse conditions often encountered in surgery.
Further objects and purposes of the invention will be apparent to persons familiar with an apparatus of this kind upon reading the following description and upon inspection of the accompanying drawings.